An inquiry into the way MPs claim expenses is expected to be launched by the Whitehall standards watchdog, it emerged today.

Members of the committee on standards in public life have been discussing holding their own investigation after the Commons voted last night to reject a reform package that would have subjected MPs' expenses claims to external audit.

A source close to the committee said that the vote, which will also allow MPs to carry on claiming for furniture for their second homes according to the so-called "John Lewis list", was "just a train wreck for the House of Commons".

A spokesman for the prime minister said that Gordon Brown was "disappointed" by the vote, which saw Brown's two parliamentary aides and 33 of his ministers reject the reform package, even though Brown was said to be in favour of it.

After the proposed reforms were rejected last night by 172 votes to 144, a majority of 28, Sir Christopher Kelly, the chairman of the committee on standards in public life, said: "I would expect the public to react very badly."

Kelly has been calling fellow committee members today to discuss an inquiry. Although the committee, which is not carrying out any other full inquiries at the moment, is not due to meet until July 16, the decision to launch an investigation could be announced sooner.

A source close to the committee said: "We thought the reform package was a good step forward and, if it was implemented, we were prepared just to monitor it. But, now that the Commons has rejected it, it is almost inevitable that we will hold our own inquiry."

Amid heated exchanges in the division lobbies last night, the Tories claimed that government whips had struck a deal with Labour backbenchers in which they were given free rein to preserve their £24,000 additional costs allowance (ACA) while voting down an above-inflation pay increase.

The Conservative leader, David Cameron, who ordered his shadow cabinet to back the reforms, was sworn at by one Labour MP as he voted.

There were also angry exchanges between George Osborne, the shadow chancellor and one of the prime minister's parliamentary aides, Ian Austin, as at least four cabinet ministers and 29 other ministers voted down the reforms.

Although Brown was said to support the proposed changes, he did not attend the Commons to vote and his two parliamentary private secretaries, Austin and Basildon MP Angela Smith, both voted against the reforms.

The row erupted after MPs heeded a call from Brown for pay restraint when they rejected, by 196 votes to 155, a proposal to raise their salaries by up to 2.3% this year and 4.7% next year. The vote means MPs will get a 2.25% pay rise this year and be denied a "catch-up" payment of £650 a year for the next three years.

Government whips were then seen nodding Labour MPs through the aye lobby when they voted on a backbench amendment, tabled by former minister Don Touhig, to preserve their expenses.

While the votes were free, whips often give an informal indication of how MPs should vote and the Commons divided broadly along party lines. Of the 172 MPs voting against the reform package, 146 were Labour and only 21 were Conservative.

The vote to reject the reforms advised by the Commons members estimate committee, means:

• MPs can continue to claim for furniture and household goods for their second homes, known as the "John Lewis list" as the Commons only authorises payments in line with the prices charged by that retailer,

• the additional costs allowance will remain, and not become an overnight expenses allowance with a £19,600 ceiling,

Asked about the result, the prime minister's spokesman said: "The prime minister has always made it clear that he is in favour of enhanced transparency for MPs' expenses.

"He's disappointed by the outcome of the vote. But this was a parliamentary matter, not a government matter. It was a free vote."

Asked why the prime minister did not vote, the spokesman said Brown was involved in important meetings and that he had decided not to abandon them because "it was clear that the option he would have voted for was going to be defeated by a significant majority".

The Tories last night criticised Brown for voting to restrain MPs' pay but not turning up for the vote on expenses.

Chris Grayling, the shadow work and pensions secretary, said: "David Cameron and the shadow cabinet voted for the abolition of the John Lewis list while Gordon Brown and his most senior ministers went awol. They are showing blatant contempt for very real public concerns."

Nick Harvey, a Liberal Democrat member of the members estimate committee, criticised the vote. "It was a total own-goal on the part of the House of Commons.

"An opportunity to put our house in order and be seen to put our house in order has been passed up. They took all the nice bits of the package but not the ones they didn't like. They took the spoonful of sugar but refused the medicine."

Touhig told Harvey: "The main thrust of this report is an audit system which is uncosted. It will cost the taxpayer millions."

The vote for pay restraint followed a heated debate in which older MPs insisted members should be paid more generously.

David Maclean, the former Tory chief whip who is MP for Penrith and Borders, said: "We have the responsibility of making mega, mega decisions and for that we are getting the level of pay of a second-tier officer in a district council."

Harriet Harman, the leader of the Commons, also announced that the government would introduce a regulation to exclude MPs' addresses from freedom of information requests.

Today Peter Kilfoyle, a Labour former minister who voted against the expenses reforms, said that he had objected to the proposals for outside auditors.

"What I was very concerned about was what was described as 'practice assurance' in which teams of people, at a very great cost in terms of time and money, would be able to trawl through individual MPs' offices," he told the BBC Radio 4 Today programme.

"Why should somebody come around my office and do an effective time and motion study on my staff when I am technically self-employed?"

Kilfoyle said he thought that there should have been an external inquiry into the expenses system. He said that the problem with the package drawn up by the members estimate committee was that it did not suit everyone, but that he sympathised with the committee because the government had been unwilling to come up with ideas of its own.

"You cannot win on this. That's why governments of all parties have dropped it on the toes of people like Nick Harvey," he said.

He added: "I am a trade unionist, have been all my life, and I want the best conditions for MPs as I wanted for the police, as I want for local government workers and everybody else. I make no exceptions."